JP2841783B2 - Ultrasonic level meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an ultrasonic level meter for measuring the liquid level of a liquid stored in a container.

<Related Art> An ultrasonic level meter that measures the height of a liquid surface is used to monitor the storage amount of a liquid such as oil, milk, or beer stored in a container.

As shown in FIG. 2 (a), a conventional ultrasonic level meter has an ultrasonic probe b disposed at an upper portion in a container a, and vertically extends from the ultrasonic probe b toward the liquid surface. An ultrasonic pulse is emitted, the reflected wave is received again by the ultrasonic probe b, and the liquid level is measured based on the time required for transmitting and receiving the ultrasonic wave. Alternatively, as shown in FIG. 2 (b), the ultrasonic probe b is immersed in the liquid and the ultrasonic pulse is emitted from the bottom in the container a. The height of the liquid level is measured based on this.

<Problem to be Solved by the Invention> However, in the configuration shown in FIG. 2 (a), when the liquid is, for example, milk or beer, when such a liquid is poured into a container, the liquid is placed on the liquid surface. Since a large number of bubbles c exist and ultrasonic waves are scattered by the bubbles c, a stable measurement result cannot be obtained.

On the other hand, in the structure shown in FIG. 2 (b), there is no influence of bubbles on the liquid surface. However, if the liquid has a large specific gravity, for example, heavy oil, when it is poured into the container a, it will be in the liquid. Since the existing bubble d does not easily float, the ultrasonic wave is attenuated by the presence of the bubble d, so that a stable measurement result cannot be obtained.

<Means for Solving the Problems> The present invention has been made in view of such circumstances, and even when bubbles exist on the liquid surface or bubbles exist in the liquid, the present invention is not limited thereto. The height of the liquid surface can be accurately measured without being affected by the height.

Therefore, the present invention has an ultrasonic probe 6 for transmitting and receiving an ultrasonic pulse, and the ultrasonic probe 6 transmits ultrasonic waves from the ultrasonic probe 6 toward the liquid surface of the liquid 2 stored in the container 1. An ultrasonic level meter for measuring the height of the liquid surface based on the time until a pulse is emitted and the reflected wave is received by the ultrasonic probe 6 again. A floating tool 8 having a lower specific gravity than the liquid disposed in the container 1 while being disposed at the bottom of the container 1;
The floating member 8 is provided with a reflecting plate 10 having a higher specific gravity than the liquid suspended in a swingable manner.

<Operation> In the above configuration, the ultrasonic pulse emitted from the ultrasonic probe 6 arranged at the bottom of the container 1 is reflected by the reflector 10 suspended from the floating tool 8, and is again returned to the ultrasonic probe. 6
Is received by Then, by measuring the time required for transmitting and receiving waves during this time, the distance m between the ultrasonic probe 6 and the reflecting plate 10 can be determined. Further, even if the height of the floating tool 8 changes in accordance with the increase or decrease of the storage amount of the liquid 2, the distance l between the floating tool 8 and the reflecting plate 10 is constant. The distance between the element 6 and the liquid surface can be determined by m + 1.

Here, the more bubbles are present near the liquid surface, the more the distance l between the floater 8 and the reflector 10 is set, the better the distance between the floats 8 and the reflector 10 will be.
Are opposed to the ultrasonic probe 6, so that they are not affected by bubbles. Further, since the ultrasonic pulse is emitted from the bottom surface side of the container 1, the influence of bubbles on the liquid surface is naturally not affected.

<Embodiment> FIG. 1 is a configuration diagram of an ultrasonic level meter according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a container, 2 denotes a liquid stored in the container 1, 3 denotes an inlet for the liquid 2, and 4 denotes an ultrasonic level meter.

The ultrasonic level meter 4 includes an ultrasonic probe 6 for transmitting and receiving an ultrasonic pulse, and a distance to a liquid surface 2a based on the time of the ultrasonic pulse transmitted and received by the ultrasonic probe 6. And a measurement unit 7 for measuring Then, the ultrasonic probe 6 is attached to the bottom outside the container 1. Further, a floating tool 8 having a specific gravity smaller than that of the liquid 2 is provided in the container 1 and floats on the liquid 2. An arm 9 having a predetermined length 1 is attached to the lower part of the float 8 by a pin or the like so as to be swingable. A reflecting plate 10 made of a metal having a specific gravity larger than that of the liquid 2 is attached to the arm 9. Fixed. Thereby, even if the float 8 swings when the liquid is injected from the inlet 3, the reflector 10 is stopped without being affected by the swing. The reflection plate 10 and the ultrasonic probe 6 face each other.

12 is a trigger pulse generator that generates a trigger pulse, 14
Is a transmitting unit that outputs a drive pulse for exciting the ultrasonic probe 6 in response to a trigger pulse, and 16 is an amplifier that amplifies and detects a signal obtained by receiving an ultrasonic echo with the ultrasonic probe 6. The receiving section 18 is a level comparing section for comparing the signal level from the receiving section 18 with a preset threshold value. Reference numeral 20 denotes a counter for counting the transmission time of the ultrasonic pulse, which starts counting in response to a trigger pulse from the ultrasonic trigger pulse generator, and counts in response to the output signal of the level comparator 18. To stop. Reference numeral 22 denotes a setting unit for providing a counter with a preset value corresponding to the distance between the float 8 and the reflection plate 10, 24 denotes a calculation unit that measures the liquid level based on the count output of the counter 20, and 26 denotes a calculation. It is a display section for displaying the result.

In the above configuration, even if the height of the floating member 8 changes according to the increase or decrease of the storage amount of the liquid 2, the distance l between the floating member 8 and the reflecting plate 10 is kept constant. Here, since the number of the bubbles 30 usually increases as it approaches the liquid surface, if the distance l between the floating tool 8 and the reflecting plate 10 is appropriately set, the reflection is performed in such a manner as to avoid the portion where the number of bubbles 30 exists. Since the plate 10 faces the ultrasonic probe 6, the plate 10 is not affected by the bubbles 30.
In addition, since the ultrasonic pulse is emitted from the bottom surface side of the container 1, even if the bubbles 32 exist on the liquid surface 2a, the influence is naturally not affected.

Therefore, when the trigger pulse is output from the trigger pulse generation unit 12, the counter 20 starts the counting operation in response thereto, while the driving pulse is output from the transmission unit 14, and this driving pulse causes the bottom of the container 2 to be output. An ultrasonic pulse is emitted from the arranged ultrasonic probe 6. Then, this ultrasonic pulse is reflected by the reflecting plate 10 suspended by the floater 8 and is received again by the ultrasonic probe 6 with little influence of the bubble 30. Then, the output from the ultrasonic probe 6 is amplified and detected by the receiving unit 16,
The level is compared with a predetermined threshold value by the level comparing section 18.

When a trigger pulse is input from the trigger pulse generator 12, the counter 20 starts counting from the preset value. When the ultrasonic echo reflected by the reflector 10 is received, its signal level is compared with the level comparing section.
Since the value exceeds the threshold value set at 18, the counter 20 stops the counting operation by the output from the level comparing section 18 at that time. As a result, the counter 20 outputs a count value corresponding to the time required to reciprocate the distance m between the ultrasonic probe 6 and the reflecting plate 10, and the count value is calculated by the next stage. It is sent to the unit 24. The calculation unit 24 is provided with correction data in consideration of the distance 1 between the float 8 and the reflector 10 and the thickness t of the bottom surface of the container 1 by the setting unit 22. Calculate the distance m + lt between the touch element 6 and the liquid level 2a of the liquid 2, and calculate the distance m + 1-t.
The value of t is displayed on the display unit 26 as the height of the liquid level 2a.

In this embodiment, the ultrasonic probe 6 is attached to the bottom surface outside the container 1.
Of course, it is also possible to measure the height of the liquid surface 2a by immersing the liquid 2 in the liquid 2.

<Effect of the Invention> According to the present invention, even when bubbles are present on the liquid surface or bubbles are present in the liquid, the height of the liquid surface can be accurately measured without being affected by them. Excellent effects such as being able to be achieved are exhibited.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an ultrasonic level meter according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional ultrasonic level meter. 1 ... container, 2 ... liquid, 4 ... ultrasonic level meter, 6 ...
... Ultrasonic probe, 8 ... Floating tool, 10 ... Reflector.

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Claims (1)

(57) [Claims] An ultrasonic probe (6) for transmitting and receiving an ultrasonic pulse is provided, and a container (1) is provided from the ultrasonic probe (6).
An ultrasonic pulse is emitted toward the liquid surface of the liquid (2) stored in the ultrasonic probe, and the reflected wave is again transmitted to the ultrasonic probe (6).
In the ultrasonic level meter for measuring the height of the liquid level based on the time until the wave is received by the ultrasonic probe (6), the ultrasonic probe (6) is arranged at the bottom of the container (1), And a reflector (10) having a specific gravity greater than that of the liquid suspended in the floater (8) and being swingably suspended on the floater (8). Characteristic ultrasonic level meter.